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<title>Chapter 1. Boost.NumericConversion</title>
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<div class="chapter">
<div class="titlepage"><div>
<div><h2 class="title">
<a name="numeric_conversion"></a>Chapter 1. Boost.NumericConversion</h2></div>
<div><div class="author"><h3 class="author">
<span class="firstname">Fernando Luis</span> <span class="surname">Cacciola Carballal</span>
</h3></div></div>
<div><p class="copyright">Copyright © 2004-2007 Fernando
      Luis Cacciola Carballal</p></div>
<div><div class="legalnotice">
<a name="numeric_conversion.legal"></a><p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
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</div></div>
<div class="toc">
<p><b>Table of Contents</b></p>
<dl class="toc">
<dt><span class="section"><a href="index.html#numeric_conversion.overview">Overview</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html">Definitions</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.introduction">Introduction</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.types_and_values">Types
      and Values</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.c___arithmetic_types">C++
      Arithmetic Types</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.numeric_types">Numeric
      Types</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.range_and_precision">Range
      and Precision</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.exact__correctly_rounded_and_out_of_range_representations">Exact,
      Correctly Rounded and Out-Of-Range Representations</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.standard__numeric__conversions">Standard
      (numeric) Conversions</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.subranged_conversion_direction__subtype_and_supertype">Subranged
      Conversion Direction, Subtype and Supertype</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_numericconversion/converter___function_object.html">converter&lt;&gt;
    function object</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_numericconversion/converter___function_object.html#boost_numericconversion.converter___function_object.synopsis">Synopsis</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/converter___function_object.html#boost_numericconversion.converter___function_object.template_parameters">Template
      parameters</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/converter___function_object.html#boost_numericconversion.converter___function_object.member_functions">Member
      functions</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic">Range
      Checking Logic</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/converter___function_object.html#boost_numericconversion.converter___function_object.examples">Examples</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_numericconversion/type_requirements_and_user_defined_types_support.html">Type
    Requirements and User-defined-types support</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_numericconversion/type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.type_requirements">Type
      Requirements</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics">UDT's
      special semantics</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.special_policies">Special
      Policies</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udts_with_numeric_cast">UDTs
      with numeric_cast</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_numericconversion/bounds___traits_class.html">bounds&lt;&gt;
    traits class</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_numericconversion/bounds___traits_class.html#boost_numericconversion.bounds___traits_class.introduction">Introduction</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/bounds___traits_class.html#boost_numericconversion.bounds___traits_class.traits_class_bounds_n_">traits
      class bounds&lt;N&gt;</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/bounds___traits_class.html#boost_numericconversion.bounds___traits_class.examples">Examples</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_numericconversion/conversion_traits___traits_class.html">conversion_traits&lt;&gt;
    traits class</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_numericconversion/conversion_traits___traits_class.html#boost_numericconversion.conversion_traits___traits_class.types">Types</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/conversion_traits___traits_class.html#boost_numericconversion.conversion_traits___traits_class.examples">Examples</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_numericconversion/numeric_converter_policy_classes.html">Numeric
    Converter Policy Classes</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.enum_range_check_result">enum
      range_check_result</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_overflowhandler">Policy
      OverflowHandler</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder">Policy
      Float2IntRounder</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter">Policy
      RawConverter</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker">Policy
      UserRangeChecker</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_numericconversion/improved_numeric_cast__.html">Improved
    numeric_cast&lt;&gt;</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_numericconversion/improved_numeric_cast__.html#boost_numericconversion.improved_numeric_cast__.introduction">Introduction</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/improved_numeric_cast__.html#boost_numericconversion.improved_numeric_cast__.numeric_cast">numeric_cast</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/improved_numeric_cast__.html#boost_numericconversion.improved_numeric_cast__.numeric_cast_traits">numeric_cast_traits</a></span></dt>
<dt><span class="section"><a href="boost_numericconversion/improved_numeric_cast__.html#boost_numericconversion.improved_numeric_cast__.examples">Examples</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="numeric_conversion/history_and_acknowledgments.html">History
    and Acknowledgments</a></span></dt>
<dt><span class="section"><a href="numeric_conversion/bibliography.html">Bibliography</a></span></dt>
</dl>
</div>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="numeric_conversion.overview"></a><a class="link" href="index.html#numeric_conversion.overview" title="Overview">Overview</a>
</h2></div></div></div>
<p>
      The Boost Numeric Conversion library is a collection of tools to describe and
      perform conversions between values of different <a class="link" href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.numeric_types" title="Numeric Types">numeric
      types</a>.
    </p>
<p>
      The library includes a special alternative for a subset of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;&gt;</span></code>, the <a class="link" href="boost_numericconversion/bounds___traits_class.html" title="bounds&lt;&gt; traits class">bounds&lt;&gt;</a>
      traits class, which provides a consistent way to obtain the <a class="link" href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.range_and_precision" title="Range and Precision">boundary</a>
      values for the <a class="link" href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.range_and_precision" title="Range and Precision">range</a>
      of a numeric type.
    </p>
<p>
      It also includes a set of <a class="link" href="boost_numericconversion/conversion_traits___traits_class.html" title="conversion_traits&lt;&gt; traits class">trait
      classes</a> which describes the compile-time properties of a conversion
      from a source to a target numeric type. Both <a class="link" href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.c___arithmetic_types" title="C++ Arithmetic Types">arithmetic</a>
      and <a class="link" href="boost_numericconversion/definitions.html#boost_numericconversion.definitions.numeric_types" title="Numeric Types">user-defined
      numeric types</a> can be used.
    </p>
<p>
      A policy-based <a class="link" href="boost_numericconversion/converter___function_object.html" title="converter&lt;&gt; function object">converter</a>
      object which uses <code class="computeroutput"><span class="identifier">conversion_traits</span></code>
      to select an optimized implementation is supplied. Such implementation uses
      an optimal range checking code suitable for the source/target combination.
    </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
          The converter's out-of-range behavior can be customized via an <a class="link" href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_overflowhandler" title="Policy OverflowHandler">OverflowHandler</a>
          policy.
        </li>
<li class="listitem">
          For floating-point to integral conversions, the rounding mode can be selected
          via the <a class="link" href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder" title="Policy Float2IntRounder">Float2IntRounder</a>
          policy.
        </li>
<li class="listitem">
          A custom low-level conversion routine (for UDTs for instance) can be passed
          via a <a class="link" href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter" title="Policy RawConverter">RawConverter</a>
          policy.
        </li>
<li class="listitem">
          The optimized automatic range-checking logic can be overridden via a <a class="link" href="boost_numericconversion/numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker" title="Policy UserRangeChecker">UserRangeChecker</a>
          policy.
        </li>
</ul></div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: April 06, 2022 at 21:05:26 GMT</small></p></td>
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